Dental ceramic frameworks can either be coloured by incorporating pigments into the ceramic material or using metal salts containing solutions which are to be applied on the surface of partially sintered dental ceramic framework.
In this respect DE 196 19 168 A1 describes a ceramic colouring solution consisting essentially of water and a palladium containing compound dissolved therein. The solution might further contain co-solvents such as alcohols, glycols, glycol ether or polyethylene glycol.
WO 2004/110959 (corresponding to US 2006/117989 A1) relates to a colouring solution for ceramic framework. The solution comprises a solvent, a metal salt and polyethylene glycol having a molecular weight in the range of 1.000 to 200.000.
DE 196 19 165 C1 describes a process for colouring ceramic paving stone with an aqueous solution containing Ti and Fe components together with complexing agents.
WO 00/46168 A1 (corresponding to U.S. Pat. No. 6,709,694 B1) refers to colouring ceramics by way of ionic or complex-containing solutions containing defined concentrations of at least one salts or complexes of the rare earth elements or of the elements of the subgroups.
The solution might contain additives like stabilizers, complex builders, pigments and beating additives.